A lot of the adequacy questions involve what kind of hunt you're going to be on. Are you hunting from a stand, or walking? Are you hunting locally, or using your yearly vacation to travel out to an area and shoot your moose?
This all bears on what kind of shots you'll be able to pass up. If you're stand hunting, you stand a lot better chance of being able to choose your shot, and take a nice seated shot with a rest for penpoint accuracy on a standing beast. A lesser caliber can work.
If you're walking 'em up, you're going to be shooting at a less optimal target.
If you're local, you can likely bring yourself to say "Not perfect-- I'll come back tomorrow." If you're an itinerent hunter, this may be your
one shot at the beast.
If this is your shot:
, then you'd best chamber a premium bullet in a proven moose caliber, or pass up the shot.
Even worse if this is your shot:
Given that moose range from quarterhorse to percheron-size or larger, I'd have to venture that .270s need not apply here.
An '06 with a good 180g would be about minimum, with a .338 and a 250 or 275g bullet being a whole lot better.
But if your moose is doing this:
, at moderate range, and you've got a .270 loaded with a heavy, quality bullet of known accuracy, I'd have trouble keeping a straight face while telling a man that a shot would be out of the question.